Home About us Contact
|
Home About us Contact | ||
|
|
||
AF Onset (af + onset)
Selected AbstractsFluctuation in Autonomic Tone is a Major Determinant of Sustained Atrial Arrhythmias in Patients with Focal Ectopy Originating from the Pulmonary VeinsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2001MARC ZIMMERMANN M.D. Autonomic Variations in Focal AF. Introduction: This study was designed to analyze dynamic changes in autonomic tone preceding the onset of sustained atrial arrhythmias in patients with focal atrial fibrillation (AF) to determine why patients with frequent discharge from the arrhythmogenic foci develop sustained AF. Methods and Results: Holter tapes from 13 patients (10 men and 3 women; mean age 53 ± 5 years) with paroxysmal "lone" AF (mean 18 ± 13 episodes per week) and a proven focal origin (pulmonary veins in all cases) were analyzed. A total of 38 episodes of sustained AF (> 30 min) were recorded and submitted to frequency-domain heart rate variability analysis. Six periods were studied using repeated measures analysis of variance: the 24,hour period, the hour preceding AF, and the 20 minutes before AF divided into four 5,minute periods. A significant increase in high-frequency (HF, HF-NU) components was observed during the 20 minutes preceding AF (P = 0.003 and 0.002, respectively), together with a progressive decrease in normalized low-frequency (LF-NU) components (P = 0.035). An increase in LF/HF ratio followed by a linear decrease starting 15 minutes before sustained AF also was observed, indicating fluctuations in autonomic tone, with a primary increase in adrenergic drive followed by a marked modulation toward vagal predominance immediately before AF onset. Conclusion: In patients with focal ectopy originating from the pulmonary veins, sustained episodes of atrial arrhythmias are mainly dependent on variations of autonomic tone, with a significant shift toward vagal predominance before AF onset. [source] Electrophysiological Differences of the Spontaneous Onset of Paroxysmal and Persistent Atrial FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2007STEFAN WEBER M.D. Background: Information about the spatiotemporal organization of atrial activity at the onset of atrial fibrillation (AF) is still limited. Methods: AF mapping was performed in 30 patients with AF (mean age 53 ± 9 years, 26 males) by deploying a noncontact mapping balloon in the left atrium (LA). Twenty-four patients had paroxysmal AF and six patients had persistent AF. Three types of AF episodes were analyzed: nonsustained AF (lasting , 30 seconds), sustained AF (lasting > 30 seconds, with spontaneous conversion or requiring internal cardioversion and subsequent stable sinus rhythm), and persistent AF episodes (stable sinus rhythm lasting , 1 minute after cardioversion). Results: A total of 101 spontaneous AF onset episodes were analyzed. Analysis of AF onset showed that there was a progressive shortening of the initial cycle lengths from nonsustained episodes to sustained episodes and to persistent AF episodes. There was an earlier and more rapid reduction in the cycle lengths from persistent episodes to sustained episodes and to nonsustained episodes of AF (P < 0.05 for persistent vs sustained and for sustained vs nonsustained episodes). The development of multiwavelet activity and disorganization of conduction occurred earlier in persistent and sustained episodes than in nonsustained AF episodes. LA size was greater in patients with persistent AF episodes compared with patients with sustained or nonsustained AF episodes. Conclusions: Electrophysiological events that develop at the onset of AF seem to be different in different types of AF. A more rapid degeneration into the fibrillatory activity was observed in persistent and sustained AF than in nonsustained AF episodes. [source] Individualized Selection of Pacing Algorithms for the Prevention of Recurrent Atrial Fibrillation: Results from the VIP RegistryPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2006THORSTEN LEWALTER Objectives: The VIP registry investigated the efficacy of preventive pacing algorithm selection in reducing atrial fibrillation (AF) burden. Background: There are few data identifying which patients might benefit most from which preventive pacing algorithms. Methods: Patients, with at least one documented AF episode and a conventional antibradycardia indication for pacemaker therapy, were enrolled. They received pacemakers with AF diagnostics and four preventive algorithms (Selection and PreventAF series, Vitatron). A 3-month Diagnostic Phase with conventional pacing identified a Substrate Group (>70% of AF episodes with <2 premature atrial contractions [PACs] before AF onset) and a Trigger Group (,70% of AF episodes with <2 PACs before AF onset). This was followed by a 3-month Therapeutic Phase where in the Trigger Group algorithms were enabled aimed at avoiding or preventing a PAC and in the Substrate Group continuous atrial overdrive pacing was enabled. Results: One hundred and twenty-six patients were evaluated. In the Trigger Group (n = 73), there was a statistically significant 28% improvement in AF burden (median AF burden: 2.06 hours/day, Diagnostic Phase vs 1.49 hours/day, Therapy Phase; P = 0.03304 signed-rank test), and reduced PAC activity. There was no significant improvement in AF burden in the Substrate Group (median AF burden: 1.82 hours/day, Diagnostic Phase vs 2.38 hours/day, Therapy Phase; P = 0.12095 signed-rank test), and little change in PAC activity. Conclusions: We identified a subgroup of patients for whom the selection of appropriate pacing algorithms, based on individual diagnostic data, translated into a reduced AF burden. Trigger AF patients were more likely responders to preventive pacing algorithms as a result of PAC suppression. [source] Magnesium Sulfate versus Placebo for Paroxysmal Atrial Fibrillation: A Randomized Clinical TrialACADEMIC EMERGENCY MEDICINE, Issue 4 2009Kevin Chu MBBS Abstract Objectives:, The objective was to investigate the efficacy of magnesium sulfate (MgSO4) in decreasing the ventricular rate in emergency department (ED) patients presenting with new-onset, rapid atrial fibrillation (AF). Methods:, A double-blinded, placebo-controlled randomized clinical trial was conducted in an adult university hospital. Patients aged ,18 years with AF onset of less than 48 hours and a sustained ventricular rate of >100 beats/min were randomized to either intravenous (IV) MgSO4 10 mmol or normal saline (NSal). Rhythm and instantaneous heart rate as measured by the monitor were recorded at baseline and every 15 minutes for 2 hours after starting the trial drug. Heart rate and rhythm were compared at 2 hours. A multilevel modeling analysis was performed to adjust for differences in baseline heart rate and any additional treatment and to examine changes in heart rate over time. Results:, Twenty-four patients were randomized to MgSO4 and 24 to NSal. Baseline heart rate was lower in the MgSO4 group (mean ± standard deviation [±SD] = 125 ± 24 vs. 140 ± 21 beats/min]. One and 3 patients in the MgSO4 and NSal groups, respectively, were given another antiarrhythmic or were electrically cardioverted within 2 hours after starting the trial drug. Heart rate (mean ± SD) at 2 hours in both MgSO4 (116 ± 30 beats/min) and NSal groups (114 ± 31 beats/min) decreased below their respective baseline levels. However, the rate of heart rate decrease across time did not differ between groups (p = 0.124). The proportion of patients who converted to sinus rhythm 2 hours post,trial drug did not differ (MgSO4 8.7% vs. NSal 25.0%, p = 0.25). Conclusions:, This study was unable to demonstrate a difference between IV MgSO4 10 mmol and saline placebo for reducing heart rate or conversion to sinus rhythm at 2 hours posttreatment in ED patients with AF of less than 48 hours duration. [source] | ||||||||||